Abstract
Since a sensor is a converter of generally nonelectrical effects into electrical signals, one and often several transformation steps are required before the electric output signal can be generated. These steps involve changes of types of energy or physical properties of materials, wherein the final step shall produce electrical signal of a desirable format. As it was mentioned in Chap. 1, generally there are two types of sensors: direct and complex. A direct sensor is the one that can directly convert a nonelectrical stimulus into electric output signal. Many stimuli cannot be directly converted into electricity, thus multiple conversion steps would be required. If, for instance, one wants to detect displacement of an opaque object, a fiber optic sensor can be employed. A pilot light beam (excitation signal) is generated by the light emitting diode (LED). Then the light flux enters the optical fiber and propagates through it, then exits toward the object and is reflected from its surface. The reflected photon flux enters the receiving optical fiber and propagates toward a photodiode, where it is detected to produce electric current representing a distance from the fiber optic end to the object. We see that such a sensor involves transformation of electrical current into photons, propagation of photons through some refractive media (the fiber), reflection from the object, propagation again through the fiber, and conversion back into electric current. Therefore, such a sensing process includes two energy conversion steps and also manipulation of light.
“The way we have to describe Nature
is generally incomprehensible to us.”
—Richard P. Feynman,
“QED. The Strange Theory of Light and Matter”
“It should be possible to explain
the laws of physics to a barmaid.”
—Albert Einstein
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Notes
- 1.
Prefix tribo- means “friction”.
- 2.
A Russian physicist of German extraction Georg Wilhelm Richmann (1711–1753) was killed in St. Petersburg during a thunderstorm experiment when a ball lightning having a size of a fist jumped from the electrometer and struck him in a forehead.
- 3.
Now, the U.S. pennies are just copper-plated (2.5 % of copper), but till 1982 they did contain 95 % of copper.
- 4.
The bold face indicates a vector notation.
- 5.
Lenz Law is named after the German scientist H.F.E. Lenz in 1834.
- 6.
Eddy currents are employed for inductive cooking. A coil positioned under a pot induces strong circular currents in the pot base. For converting eddy currents into thermal energy, the base shall have not too high and not too low electrical resistance. That is why neither glass or ceramic, nor cupper or aluminum cookware can be used for inductive cooking.
- 7.
Excluding superconductors which are beyond the scope of this book.
- 8.
Since resistance of a metal increases with temperature, a tungsten filament in a light bulb acts as a self-regulator of temperature, so the filament does not burn out. When temperature increases, the resistance goes up, and the current drops, causing the temperature to come down. If coefficients α for metals were negative, the filaments would instantly burn out and we would not have incandescent electric lights.
- 9.
See Sect. 17.1.
- 10.
The term is based on a similarity between the electrode shape and shapes of human fingers (digits).
- 11.
The complete set of coefficients also includes shear stress and the corresponding d-coefficients.
- 12.
The electrode area, not the crystal area! Piezoinduced charge can be collected only over the area covered by the electrode.
- 13.
Remember, a piezoelectric sensor is an AC device, so it will not respond to a constant or slowly changing force.
- 14.
This is a misnomer as the prefix ferro, meaning iron, is used despite the fact that most ferroelectric materials do not have iron in their lattice. It is used by analogy with ferromagnetics.
- 15.
Electric permittivity is the same thing as dielectric constant.
- 16.
A Thompson effect was discovered by William Thompson around 1850. It consists of absorption or liberation of heat by passing current through a homogeneous conductor which has a temperature gradient across its length. Unlike the Joule effect (liberated hear is proportional to square of current), the heat is linearly proportional to current. Heat is absorbed when the current and heat flow in opposite directions, and heat is produced when they flow in the same direction.
- 17.
Or perhaps the same material in two different states, for example, one under strain, the other is not.
- 18.
Joule heat is produced when electric current passes in any direction through a conductor having finite resistance. Released thermal power of Joule heat is proportional to squared current: P = i 2/R, where R is resistance of a conductor.
- 19.
There is an anecdote about the American physicist R. W. Wood (1868–1955). His friend, a theatrical director from New York, asked Wood to invent a mysterious sound effect for a play about time travel. Wood built a huge organ pipe (sort of a whistle) for the infrasonic frequency of about 8 Hz. When during a dress rehearsal, Wood activated the pipe, the entire building and everything in it started vibrating. The terrified audience ran out to the street, feeling uncontrollable fear and panic. Needless to say, the pipe was never used during performances.
- 20.
More precisely, not “by him” but rather “for him”. The Duke was obsessed with new technologies, and had several hygrometers, barometers, thermometers, and telescopes installed in his Pitti palace in Florence.
- 21.
A calorie that measures energy in food is actually equal to 1000 physical calories that is called a kilocalorie.
- 22.
After all, Fahrenheit was a toolmaker and for him 96, but not 100, was a convenient number because to engrave the graduation marks, he could easily do so by dividing a distance between the marks by two: 96, 48, 24, etc. With respect to nationality of the blood, he did not care if it was blood of an Englishman or not. Now, it is known that blood temperature of a healthy person is not really constant. It varies between approximately 97 and 99.5 °F (36 and 37.5 °C) but during his times, Fahrenheit could not find a better thermostat than a human body.
- 23.
There is a difference of 0.01° between the Kelvin and Celsius scales, as Celsius’ zero point is defined not at a triple point of water as for the Kelvin, but at temperature where ice and air-saturated water are at equilibrium at atmospheric pressure.
- 24.
This assumes that there is no phase change during warming up, like from solid to liquid.
- 25.
Likely, this is because of a better compatibility between the animal protein molecules and structures of the water crystals at that temperature that is manifested by the water specific heat.
- 26.
In 1918, Max K. E. L. Planck (Germany, Berlin University) was awarded Nobel Prize in recognition of his services he rendered to the advancement of Physics by his discovery of energy quanta.
- 27.
In 1911, Wilhelm Wien (Germany, Würtzburg University) was awarded Nobel Prize for his discoveries regarding the laws governing the radiation of heat.
- 28.
Here we discuss the so-called thermal sensors as opposed to quantum sensors that are described in Chap. 14.
- 29.
This simplified analysis assumes that there are no other objects in the sensor’s field of view.
- 30.
Dual-band detectors use two narrow spectral ranges to detect the IR flux. Then, by using a ratiometric technique of a signal processing, temperature of an object is calculated. During the calculation, emissivity and other multiplicative constants are cancelled out.
- 31.
In a thermally balanced IR sensor, the sensor’s temperature is constantly controlled (warmed up or cooled down) to bring the net thermal flux close to zero. Then, according to Eq. (4.138), the emissivities are multiplied by zero and thus their values no longer make any difference.
- 32.
Normal means perpendicular to surface.
References
Halliday, D., et al. (1986). Fundamentals of physics (2nd ed.). New York: John Wiley & Sons.
Crotzer, D., et al. (1993) Method for manufacturing hygristors. U.S. Patent No. 5,273,777.
Meissner, A. (1927). Über piezoelectrische Krystalle bei Hochfrequenz. Zeitschrift für Technische Physik, 8(74).
Neubert, H. K. P. (1975). Instrument transducers. An introduction to their performance and design (2nd ed.). Oxford: Clarendon.
Radice, P. F. (1982). Corona discharge poling process. U.S. Patent No. 4,365,283.
Southgate, P. D. (1976). Room-temperature poling and morphology changes in pyroelectric polyvinylidene fluoride. Applied Physics Letters, 28, 250.
Jaffe, B., et al. (1971). Piezoelectric ceramics. London: Academic.
Mason, W. P. (1950). Piezoelectric crystals and their application to ultrasonics. New York: Van Nostrand.
Megaw, H. D. (1957). Ferroelectricity in crystals. London: Methuen.
Oikawa, A., et al. (1976). Preparation of Pb(Zr, Ti)O3 thin films by an electron beam evaporation technique. Applied Physics Letters, 29, 491.
Okada, A. (1977). Some electrical and optical properties of ferroelectric lead-zirconite-lead-titanate thin films. Journal of Applied Physics, 48, 2905.
Castelano, R. N., et al. (1979). Ion-beam deposition of thin films of ferroelectric lead-zirconite-titanate (PZT). Journal of Applied Physics, 50, 4406.
Adachi, H., et al. (1986). Ferroelectric (Pb, La)(Zr, Ti)O3 epitaxial thin films on sapphire grown by RF-planar magnetron sputtering. Journal of Applied Physics, 60, 736.
Ogawa, T., et al. (1989). Preparation of ferroelectric thin films by RF sputtering. Journal of Applied Physics, 28, 11–14.
Roy, D., et al. (1991). Excimer laser ablated lead zirconite titanate thin films. Journal of Applied Physics, 69, 1.
Yi, G., et al. (1989). Preparation of PZT thin film by sol-gel processing: Electrical, optical, and electro-optic properties. Journal of Applied Physics, 64, 2717.
Tamura, M., et al. (1975). Electroacoustical transducers with piezoelectric high polymer. Journal of the Audio Engineering Society, 23(31), 21–26.
Elliason, S. (1984). Electronic properties of piezoelectric polymers. Report TRITA-FYS 6665 from Dept. of Applied Physics, The Royal Inst. of Techn., Stockholm, Sweden.
Dargahi, J. (2000). A piezoelectric tactile sensor with three sensing elements for robotic, endoscopic and prosthetic applications. Sensors and Actuators A: Physical, 80(1), 1–90.
Kawai, H. (1969). The piezoelectricity of poly (vinylidene fluoride). Japanese Journal of Applied Physics, 8, 975–976.
Meixner, H., et al. (1986). Infrared sensors based on the pyroelectric polymer polyvinylidene fluoride (PVDF). Siemens Forsch-u Entwicl Ber Bd, 15(3), 105–114.
Ye, C., et al. (1991). Pyroelectric PbTiO3 thin films for microsensor applications. In: Transducers‘91 International Conference on Solid-State Sensors and Actuators. Digest of Technical Papers (pp. 904–907). ©IEEE
Beer, A. C. (1963). Galvanomagnetic effect in semiconductors. In F. Seitz & D. Turnbull (Eds.), Suppl. to solid state physics. New York: Academic.
Putlye, E. H. (1960). The Hall effect and related phenomena. In C. A. Hogarth (Ed.), Semiconductor monographs. London: Butterwort.
Williams, J. (1990). Thermocouple measurement, AN28. In: Linear applications handbook. © Linear Technology Corp.
Seebeck, T. (1822–1823). Magnetische Polarisation der Metalle und Erze durch Temperatur-Differenz. Abhaandulgen der Preussischen Akademic der Wissenschaften (pp. 265–373).
Benedict, R. P. (1984). Fundamentals of temperature, pressure, and flow measurements (3rd ed.). New York: John Wiley & Sons.
LeChatelier, H. (1962). Copt. Tend., 102, 188629. In: D. K. C. MacDonald (Eds.), Thermoelectricity: An introduction to the principles. New York: John Wiley & Sons.
Carter, E. F. (1966). Dictionary of inventions and discoveries. In F. Muller (Ed.), Crane. New York: Russak.
Peltier, J. C. A. (1834). Investigation of the heat developed by electric currents in homogeneous materials and at the junction of two different conductors. Annals of Physical Chemistry, 56(2nd ser.), 371–386.
Thomson, W. (1854, May). On the thermal effects of electric currents in unequal heated conductors. Proceedings of the Royal Soc. (Vol. VII).
Manual on the use of thermocouples in temperature measurement. (1981). ASTM Publication code number 04-470020-40. Philadelphia: ASTM.
Doebelin, E. O. (1990). Measurement systems: Application and design (4th ed.). New York: McGraw-Hill.
Holman, J. P. (1972). Heat transfer (3rd ed.). New York: McGraw-Hill Book.
Fraden, J. (2002). Blackbody cavity for calibration of infrared thermometers. U.S. Patent No. 6447160.
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Fraden, J. (2016). Physical Principles of Sensing. In: Handbook of Modern Sensors. Springer, Cham. https://doi.org/10.1007/978-3-319-19303-8_4
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